Suchergebnisse

The effects of nitrogen (N) dose and urea source on forage mass (FM), percentage of dry matter of leaf blades (LBDMP), stem (SDMP), and dead material (DMDMP), and the forage accumulation rate (FAR) of Panicum maximum 'Massai' (massai grass) were evaluated. We set up an experiment with a completely randomized block design in a factorial arrangement (3×2) + 1, consisting of three doses (100, 200, and 400 kg ha–1 year–1), two urea sources (common and coated with Policote®), and a control treatment, in five consecutive climatic seasons, including the summers of 2011/2012 (summer I), autumn, winter, and spring of 2012, and the summers of 2012/2013 (summer II). We found an interaction effect between N dose, urea source, and season (p < 0.05). LBDMP linearly increased during dry periods (autumn and winter) and SDMP in autumn and DMDMP in winter linearly decreased when coated urea were used. FAR showed a linear increase with the use of both urea sources, except for common urea in autumn, and the increases in the winter were owing to a greater contribution of leaf blades to FM. The use of coated urea for N fertilization linearly increases FAR in all seasons of the year and improves the morphological composition of the forage of massai grass, mainly in dry seasons.

The objective of this study was to evaluate the effect of nitrogen and potassium fertilization on the morphogenetic and structural characteristics and production of Urochloa ruziziensis in two summer seasons (summer 1, 2010–2011and summer 2, 2011–2012) and the autumn and spring of 2011. A randomized complete block design with four treatments (0, 120, 240, and 360 kg ha-1 year-1 of N and K2O) and five replications was used, with repeated measurements in each season, in a split plot arrangement. The treatments were allocated to the plots and the seasons of the year to the subplots. The phyllochron (PHY),leaf appearance rate (LAR), leaf elongation rate (LER), stem elongation rate (SER), tiller population density (TPD), tiller appearance rate (TAR), tiller mortality rate (TMR), leaf growth rate (LGR), stem growth rate (SGR), senescence rate (SR), forage accumulation rate (FAR), and leaf accumulation rate (LAR) of Urochloa ruziziensis were evaluated. There was a positive quadratic effect for the PHY and ELR, with maximum values of 4.3 days leaf-1 and 0.43 cm tiller-1 day-1, respectively. While the SER increased linearly (0.0012 cm day-1 kg-1 of N and K2O) during summer 2. The TPD, TAR, and TMR increased linearly (averages of 1.53 tillers m-2, 0.04% and 0.02% per kg of N and K2O, respectively) with nitrogen and potassium fertilization during spring and both summer seasons. The LGR, SGR, and SR also increased linearly with N and K2O application rates during summer 2 (0.2809, 0.0082, and 0.0411 kg DM ha-1 day-1, per kg of N and K2O, respectively), while the FAR and LAR increased in a quadratic positive form (maximum values of 175 and 129 kg dry matter (DM) ha-1, corresponding to 294 and 237 kg ha-1 of N and K2O, respectively) during summer 2. Urochloa ruziziensis is a forage plant with a high DM production capacity during the summer and a high seasonal forage production.

Under the hypothesis that modifying nitrogen sources and doses could increase nitrogen fertilization efficiency and productivity and improve forage quality, this study aimed to evaluate the morphological composition, structural characteristics and chemical composition of Panicum maximum cv. Massai forage cultivated under different urea sources (common and coated with Policote®) and nitrogen doses (200, 400 and 600 kg ha-1 year-1) during the autumn, winter and spring of 2014 and the summer and autumn of 2015. The experiment was carried out in Seropédica, RJ, under a randomized complete block design in a factorial arrangement (3x2) + 1 with four replications. High nitrogen rates promoted higher percentages of leaf blade dry mass and lower percentages of dead material dry mass in the forage mass and provided higher tiller population density and forage accumulation rate of Massai grass during the studied seasons. The use of coated urea promoted higher levels of crude protein in the forage than did the use of common urea in all seasons. The intensification of nitrogen fertilization reduced the nitrogen use efficiency but benefitted the structural characteristics, forage accumulation and chemical composition of Massai grass forage. The use of coated urea promoted greater of nitrogen use efficiency during all seasons of the year.

The effect of dietary inclusion of increasing levels of Flemingia macrophylla hay on the yield, composition and fatty acid profile of milk from Saanen x Boer goats was evaluated. The diets were composed of 40% concentrate and 60% forage. The treatments were defined by the level of inclusion of Flemingia hay in the diet (0, 80, 160, 240 and 320 g kg-1 dry matter) in replacement of the Cynodon dactylon cv. Tifton-85 hay, distributed according to a 5 x 5 Latin Square design. The inclusion of Flemingia in the diet did not change the milk yield or milk fat content but promoted a quadratic effect on the fat yield. A quadratic effect was observed on the milk protein and lactose contents, but this effect was not reflected in the daily production of these components. The concentrations of vaccenic, rumenic, elaidic and trans-10 C18:1 fatty acids in milk fat increased linearly in response to the dietary inclusion of Flemingia, whereas the contents of palmitic, stearic, oleic, linoleic and ?-linolenic fatty acids were not modified. A linear reduction was observed in the lauric and myristic fatty acids concentrations, which was accompanied by a reduction in the atherogenic index of milk fat. A quadratic effect was also observed on the trans-10, cis-12 CLA milk fat content in response to the inclusion of Flemingia in the diet, as well as a linear increase in the apparent transfer of ?-linolenic acid from the diet to milk. The inclusion of up to 320 g kg-1 of Flemingia hay as a replacement for Tifton-85 hay in the Saanen x Boer dairy goat diet does not modify the milk production and improves the nutritional quality of milk fat by increasing the contents of rumenic and vaccenic acids beneficial to human health and reducing the concentrations of hypercholesterolemic fatty acids.